How best to find work experience during uni years?

Title says it all really. I want to try and pick up a good amount of experience whilst I'm at uni (I do CS BTW), but I have no idea how best to go about it. Companies don't always seem to post about work experience as such (I'm referring more to the week long work experience programs that some companies have), as it's more oriented around placements, which I'll look into more as placement year comes up. But is there a good way to find something like week long work experience programs?